1. Field of the invention
The present invention relates to an alignment device and method and, more particularly, to a device and method, which can be suitably applied to alignment between a photosensitive substrate and a mask in the manufacture of a liquid crystal display device using a projection exposure apparatus.
2. Related Background Art
A conventional alignment device of this type attains alignment by image processing. More specifically, as shown in FIG. 8, the alignment device picks up images of alignment marks 1 and 2 disposed on the mask surface and the photosensitive substrate surface using an image detector such as a CCD camera independently or simultaneously. Subsequently, the alignment device detects the positions of the alignment marks 1 and 2 in the picked-up image, and calculates the relative distance between the alignment marks 1 and 2. Alternatively, when the positional relationship (e.g., the distance) between a predetermined point in the screen and each alignment mark is measured, the alignment device measures the position of the predetermined point in advance, then measures the position of the alignment mark with respect to that point, and compares the measured position of the alignment mark with the design position of the alignment mark.
This method can detect the degree of a deviation of the photosensitive substrate from the screen having reference lines in a lattice pattern (FIG. 8). The alignment device attains alignment between a mask and a photosensitive substrate on the basis of the relative distance or the distance from the predetermined point.